Method of tumbling barrel finishing and material and production thereof



Patented Apr. 6, 1948,

UNITED STATES PATENT METHOD OF TUM'BLING BARREL FINISH- ING AND MATERIAL THEREOF OFFICE AND PRODUCTION Carl B. Castle, Sturgls, Micln, assignor to The Sturgis Products Company, corporation of Michigan Sturgis, Mich, a

No Drawing. Application January 12, 1946,

Serial No. 640,982

12 Claims.

' regularities employing limestone fragments as an aggregate, the same limestone fragments employed to produce a smooth and lustrous finish on thework by tumbling methods, and the process repeated with a second batch of work employing the same limestone fragments with suchadditional fragments as may be desired.

Second, to provide a method of finishing parts which enables the removal therefrom of ,fiash, sharp corners and other undesirable surface irregularities and the final polishing thereof without removing the aggregate and the work from the tumbling barrel.

Third, to provide a method of finishing which results in a smooth and lustrous finish in a relatively short period as compared with usually practiced methods and very economically.

Fourth, to provide a new tumbling material and a new method of producing the same.

Further objects and advantages will appear from the following description. The invention is defined and pointed out in the claims.

The applicant is familiar with the methods and materials of the Balz and Davidson Patents Nos. 2,318,678, 2,318,579, and 2,318,581, all issued May 11, 1943, disclosing the use of irregular fragments of crushed limestone of a-plurality of sizes and shapes and of the commercial developments and uses of the inventions of such patents.

.The applicant employs as an aggregate or as polishing elements irregular fragments of crushed limestone of varying sizes and shapes and removes the sharp points and edges thereof by tumbling, with or without an abrasive powder. The fragments are then washed to remove the abrasive, if abrasive has been used, and in any event the fine residuum of the tumbling. The limestone fragments desirably vary in size from approximately. to 2". The applicant employs the word limestone in the broadest sense of its usage and as the term is generally used commercially in the stone industry to include stone having a high content of calcium carbonate and/or magnesium carbonate, sometimes designated magnesium limestone dolomite and/or the crystallized and metamorphic limestones commonly classed as marble.

The limestone fragments are placed in a tumbling barrel with the work, the volume of limestone fragments preferably substantially exceeding the volume of the work so that the work is well surrounded and immersed in the limestone fragments.

A soapy solution with or without a powdered abrasive material is then introduced and the mass tumbled to remove flash, sharp corners and surface irregularities from the work, the soapy solution preferably having pH exceeding 11.0. The

tumbling is continued until flash, sharp corners and the like have been removed from the work. This period of operation depends, as willbe appreciated, from the character of the work, that is, whether it is steel or hard metal or relatively soft metal such as for example zinc. Non-metallic work may also be treated. After the work has been tumbled to the desire degree to remove the flash, sharp corners and surface irregularities, the fluid is drawn off and the work, the limestone fragments and the tumbling compartment washedto remove the residual material. I then introduce a solution, desirably a soapy solution, and lignin sulphonate. The commercial product known as Goulac may be used as the source of "the lignin sulphonate.

There are other commercial materials on the market which may be used in lieu of the material sold under the trade name Goulac. The pH of this solution is less than 10.5, the pH of common soap solutions commonlyranging from .9.7 to 10.2. However, it is desirable that the pH should be above 7.0

With this solution the work is again tumbled, and this results in the limestone fragments becoming coated with a film or coating which constitutes a lubricating and polishing surface, the irregularities of the limestone which would result in an abrasive action being filled in and covered. The result is that a polished and lustrous finish is produced on the work. This lubricating and polishing coating on the limestone fragments includes a precipitated insoluble calcium magnesium soap resulting from the reaction'of the soluble calcium and magnesium salts of the Goulac with the water soluble soaps of the solution. By a preferential attraction this precipitated insoluble soap coats the fragments of limestone as the tumbling proceeds. It is prob able that this preferential attraction is initiated by a reaction of the soapy solution with the Ilime-,

stone fragments.

When the desired finish is attained, the solution is drawn off and the work separated from the limestone fragments and the limestone fragtwo steps in the tumbling charge or load and 4 3 ments used with another batch of work with a soapy solution and a powdered abrasive if desired, the soapy solution having a pH exceeding 11.0 which results in removing the coating from the limestone fragments. The tumbling is continued until the sharp corners, flash and other irregularities of the work which it is desired to remove, are removed when the washing is repeated and the step of introducing the solution reacting with the limestone to produce the coating on the limestone is repeated.

Ligno-sulphonates other than Goulac might be substituted and even certain soaps without additions get fairresults. It appears desirable to use a soapcontaining large amounts of alkaline oleates such as the sodium or potassium soap of oleic acid. Tallow soap or soaps which contain other fatty acids may also be used. Low titer soaps are more desirable than the high titer soaps but either may be used, depending on operating conditions such as temperature and the like. As stated, the pH of the soap in the second or coating step may vary. considerably, but it should be such as to permit the reaction with the limestone and the resulting coating deposit.

By coating the limestone through this reaction the limestone fragments are economically coated, and although the coating is desirably in the nature of a flhn, it is effective for the purpose and the work produced has a very high quality.

It will be apparent that the material which results in the practicing of the second step could be produced outside of the actual tumbling operation and then used as a finishing aggregate. However, one of the desirable features is that of economy resulting from thecarrying on of 1iglic e fact that this may be made a continuous operation, that is, one batch processed after another, additions being'made to the limestone aggregate as may be required to maintain the volume.

As I have stated, I use the term limestone" in its broad sense, comprehending stone of the limestone group generally considered as belonging to this group because of their chemical composition.

Fragments of shell, such for example, as clam shell, may be used particularly for some work, as they have a high calcium content and coat similarly to the limestone when the method is followed, or the shell fragments may be used with the stone fragments for certain work.

I have described my invention in such detail as I believe will enable those skilled in the art to practice the same with various kinds of metal parts and with plastics or the like.

and separating the work from the limestone fragments and reusing the limestone fragments with another batch of work and a soapy solution having a pH exceeding 11.0 to remove the coating from the limestone.

2. The method of polishing comprising the steps of tumbling the work with irregular fragments of limestone, a soapy solution having a pH exceeding 11.0. and a powdered abrasive material, to remove flash, sharp comers and surface irregularities from the work, drawing off the fluid, and washing the work, the limestone fragments and the tumbling container to remove the powdered residual material, introducing a soapy solution having a pH of less than 10.5 and containing lignin sulphonate, and again tumbling and continuing the tumbling after the limestone frag- Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. The method of polishing comprising the steps of tumbling the work with irregular fragments of limestone, a soapy solution having a pH exceeding 11.0 and a powdered abrasive material, to remove flash, sharp comers and surface irregularities from-the work, drawing off the fluid, and washing the work, the limestone fragments and the tumbling container to remove the powdered residual material, introducing a soapy solution having a pH of less than 10.5 and containing lignin sulphonate, and again tumbling and continuing the tumbling after the limestone fragments have as a result of the reaction of the solution with the limestone become coated with a fllm constituting a lubricating and polishing surface, then withdrawing the second solution ments have as a result of the reaction of the solution with the limestone become coated with a fllm Y constituting a lubricating and polishing surface.

3. The method of polishing comprising the steps of tumbling the work with irregular fragments of limestone, a soapy solution and a powdered abrasive material to remove flash, sharp corners and surface irregularities from the work, drawing off the fluid, and washing the work and the limestone fragments, introducing a soapy solution containing lignin sulphonate, and again tumbling and continuing the tumbling after the limestone fragments have as a result of the reaction of the solution with the limestone become coated with a film constituting a lubricating and polishing surface, then withdrawing the second solution and separating the work from the limestone Iragments and re-using the limestone fragments with another batch of work and a soapy solution acting to remove the coating from the limestone.

4. The method of polishing comprising the steps of tumblingthe work with irregular fragments of limestone, a soapy solution and a powdered abrasive material to remove flash, sharp corners and surface irregularities from the work, drawing off the fluid, and washing the work and the limestone fragments, introducing a soapy solution containing lignin sulphonate, and again tumbling and continuing the tumbling after the limestone fragments have as a result of the reaction of the solution with the limestone become coated with a fllm constituting a lubricating'and polishing surface.

5. The method of polishing comprising the steps of tumbling the work with fragments of limestone to remove flash, sharp corners and surface irregularities from the work, introducing a solution which reacts with the limestone to cover the limestone fragments with a coating, fllling and covering the abrasive surface irregularities of the limestone, and again tumbling and continuing the tumbling after the limestone fragments have acquired such coating, separating the work from the limestone, removing the residue of such solution, and using such limestone fragments with another batch of work and with a solution acting to remove the coating from the limestone fragafter the limestone fragments have aquired such coating.

7. The method of polishing comprising the steps of tumbling the work with fragments of stone of the limestone group and of widely varying irregular outline and sizes and having the,

sharp points and edges thereof removed without destroying the shape thereof with a soapy solu-- tion having a pH of less than 10.5 and containing lignin sulphonate, the solution reacting with the stone-to form a film thereon and produce a lubricated burnishing surface thereon as compared to the abrasive character of the uncoated stone fragments.

8. The method of producing tumbling material comprising the steps of removing the sharp edges and corners of fragments of fractured limestone by tumbling the same, tumbling such treated fragments of limestone with a soapy solution having a pH of less than 10.5 which reacts with constituents of the limestone and contain ing lignin sulphonate whereby the limestone fragments are coated with a film constituting a source of lubrication and filling and covering the irregularities of the limestone which would otherwise have an abrasive action.

9. The method of producing tumbling material comprising the steps of tumbling fragments of limestone with a solution which reacts with constituents of the limestone and containing lignin sulphonate to coat the limestone with a film and covering the irregularities of the limestone which would otherwise have an abrasive action.

prising limestone fragments ofv irregular sizes and shapes and having the sharp points and edges thereof removed, covered with a film or coating of the reactance residue of the limestone and soap and lignin sulphonate.

12. A'tumbling material for polishing comprising stone fragments of the limestone group,

of irregular sizes and shapes and having the sharp points and edges thereof removed, covered with a film or coating of the reactance residue of the stone and soap containing substantial amounts of alkaline oleates.

CARL H. CASTLE.

REFERENCES CITED The following references are ofrecord in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,318,579 Balz et a1 May 11, 1943 2,318,581

Balz et a1 May 11,. 1943 

